splunk-security_content/docs/_posts/2021-09-10-getnettcpconnection_with_powershell_script_block.md

title, excerpt, categories, last_modified_at, toc, toc_label, tags

title	excerpt	categories	last_modified_at	toc	toc_label	tags
GetNetTcpconnection with PowerShell Script Block	System Network Connections Discovery	Endpoint	2021-09-10	true		System Network Connections Discovery Discovery Splunk Enterprise Splunk Enterprise Security Splunk Cloud

Try in Splunk Security Cloud{: .btn .btn--success}

Description

The following analytic utilizes PowerShell Script Block Logging (EventCode=4104) to identify the execution of the Get-NetTcpconnection commandlet. This commandlet is used to return a listing of network connections on a compromised system. Red Teams and adversaries alike may use this commandlet for situational awareness and Active Directory Discovery.

• Type: Hunting
• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel:
• Last Updated: 2021-09-10
• Author: Mauricio Velazco, Splunk
• ID: 091712ff-b02a-4d43-82ed-34765515d95d

ATT&CK

ID	Technique	Tactic
T1049	System Network Connections Discovery	Discovery

Search

`powershell` EventCode=4104 (Message = "*Get-NetTcpconnection*") 
| stats count min(_time) as firstTime max(_time) as lastTime by EventCode Message ComputerName User 
| `security_content_ctime(firstTime)` 
| `getnettcpconnection_with_powershell_script_block_filter`

Macros

The SPL above uses the following Macros:

• security_content_ctime
• powershell

Note that getnettcpconnection_with_powershell_script_block_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required field

• _time
• EventCode
• Message
• ComputerName
• User

How To Implement

To successfully implement this analytic, you will need to enable PowerShell Script Block Logging on some or all endpoints. Additional setup here https://docs.splunk.com/Documentation/UBA/5.0.4.1/GetDataIn/AddPowerShell#Configure_module_logging_for_PowerShell.

Known False Positives

Administrators or power users may use this PowerShell commandlet for troubleshooting.

Associated Analytic story

• Active Directory Discovery

Kill Chain Phase

• Reconnaissance

RBA

Risk Score	Impact	Confidence	Message
15.0	30	50	Network Connection discovery on dest by user

Reference

• https://attack.mitre.org/techniques/T1049/
• https://docs.microsoft.com/en-us/powershell/module/nettcpip/get-nettcpconnection?view=windowsserver2019-ps

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

• https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1049/AD_discovery/windows-powershell.log

source | version: 1